Robert A. Heinlein

A Hugo winner for best Novel, awarded in 1957 & a pretty short book at 143 pages. It's written in a fairly chatty style, later we find that Lawrence Smith, aka The Great Lorenzo, is relating the story in his own words from several years after the events therein.

The basic plot is that Lorenzo, an out of work actor, is employed to impersonate a political leader who has been kidnapped just as he's on the brink of a major political break through.